Parylenes are polymers with particularly favourable properties for use in specifically resistant coatings. The commonly used term ‘parylenes’ is short for the chemically correct name poly-para-xylylene. Parylenes are characterised by their extremely high resistance to almost all aggressive media and solvents. Coats of a small coat thickness provide for an extraordinarily low water permeability. Furthermore, they are very ageing-resistant. In the vacuum, parylene coats are generated directly on the substrate by polymerisation of the monomer. Parylenes can cover ultra-fine structures. These outstanding properties make parylene a preferred coating material for electronic components that are subject to special requirements in terms of operational safety, resistance to ageing, weathering and chemicals.